U.S. patent application number 10/484665 was filed with the patent office on 2005-02-03 for method and device for applying compressive and/or tractional forces to essentially rod-shaped workpieces consisting of electroconductive and/or magnetisable material.
Invention is credited to Bilstein, Peter, Illgen, Lothar, Witte, Werner.
Application Number | 20050022571 10/484665 |
Document ID | / |
Family ID | 7692823 |
Filed Date | 2005-02-03 |
United States Patent
Application |
20050022571 |
Kind Code |
A1 |
Bilstein, Peter ; et
al. |
February 3, 2005 |
Method and device for applying compressive and/or tractional forces
to essentially rod-shaped workpieces consisting of
electroconductive and/or magnetisable material
Abstract
The disclosure relates to a method for applying compressive
and/or tractional forces to an essentially rod-shaped workpiece,
according to which a mechnical engagement in the rod-shaped
workpiece can be avoided. To this end, the method involves applying
compressive and/or tractional forces to an essentially rod-shaped
workpiece including an electroconductive and/or magnetizable
material. A magnetic field is applied to the workpiece, including a
gradient in the direction of the force to be applied. The
disclosure also relates to a device for applying compressive and/or
tractional forces to an essentially rod-shaped workpiece including
electroconductive and/or magnetizable material. The device includes
a coil arrangement that is supplied by a current and is designed to
produce a magnetic field having a gradient.
Inventors: |
Bilstein, Peter; (Menden,
DE) ; Illgen, Lothar; (Iserlohn, DE) ; Witte,
Werner; (Unna, DE) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
|
Family ID: |
7692823 |
Appl. No.: |
10/484665 |
Filed: |
September 13, 2004 |
PCT Filed: |
October 6, 2002 |
PCT NO: |
PCT/EP02/06297 |
Current U.S.
Class: |
72/67 |
Current CPC
Class: |
B21C 1/32 20130101; B21C
1/305 20130101; B21C 23/005 20130101; B21F 23/00 20130101 |
Class at
Publication: |
072/067 |
International
Class: |
B21B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2001 |
DE |
101-35-876.8 |
Claims
1-13. (Cancel)
14. Method for applying compressive and/or tractive forces on a
rod-shaped workpiece comprising electrically conductive and/or
magnetizable material, the method comprising: applying a magnetic
field on the workpiece comprising a gradient pointing in a
direction of a force to be applied, wherein a current flowing
through a coil arrangement is modified periodically as a function
of time with a frequency that corresponds to a resonance frequency
for a maximum force to be applied on the workpiece.
15. Method pursuant to claim 14, wherein the magnetic field is
generated by the coil arrangement comprising at least two coils
that are arranged around the workpiece axially spaced from each
other, wherein wherein the at least two coils are flowed through by
a current, respectively, for the purpose of generating different
magnetic fields.
16. Method pursuant to claim 15, wherein the at least two coils
each are flowed through by a current, wherein the currents flowing
through the individual coils are out-of-phase and/or have different
current strengths.
17. Method pursuant to claim 15, wherein the current flowing
through the coil arrangement is modified as a function of time.
18. Method pursuant to claim 15, wherein the coil arrangement is
cooled.
19. Method pursuant to claim 14, wherein the workpiece is
electrically conductive and subjected to current through flow.
20. Method pursuant to claim 14, wherein the workpiece is
cooled.
21. Method pursuant to claim 14, wherein the compressive and/or
tractive forces are applied to the workpiece for the purpose of
transporting and/or forming the same.
22. Device for applying compressive and/or tractive forces on a
rod-shaped workpiece comprising electrically conductive and/or
magnetizable material, the device comprises: a coil arrangement
that is adapted to be acted upon by current for generating a
magnetic field comprising a gradient pointing in the direction of
the force to be applied on the workpiece.
23. Device pursuant to claim 22, wherein the coil arrangement
comprises at least two coils, which can be acted upon by a current
that can be adjusted individually for each coil by means of a
control unit.
24. Device pursuant to claim 23, wherein the coils are arranged
around a workpiece path in a concentric manner and in the axial
direction of the rod-shaped workpiece at a distance from each
other, wherein along said path compressive and/or tractive forces
are supposed to be applied on the workpiece.
Description
[0001] The invention relates to a method for applying compressive
and/or tractive forces on an essentially rod-shaped workpiece
consisting of electrically conductive and/or magnetizable material.
The invention moreover relates to a device for executing the
method.
[0002] Essentially rod-shaped workpieces in the sense of this
invention are such workpieces whose expansion in the axial
direction clearly exceeds the dimensions in the lateral directions.
This can be for example pipes, rods, bars, profile struts or flat
strips.
[0003] To move such workpieces for example within the framework of
a machining or manufacturing system, it is necessary to apply
compressive and/or tractive forces on these workpieces. Similarly
such forces are necessary especially during forming processes where
the workpieces for example are pressed or pulled through molding
dies to develop the profile or change the diameter. This is
required e.g. when drawing pipes, wherein a pipe with a diameter D1
before the drawing process is formed by being pulled through a die
or a drawing plate while shaping the material into a pipe with a
smaller diameter D2 than the diameter D1. For such an operation it
is necessary to apply an appropriate tractive force on the
workpiece to be formed, in the example mentioned this is the pipe
that is to be drawn, in order to achieve on one hand the shape and
on the other hand a conveying process of the workpiece to be
formed. In familiar forming systems, for example for drawing pipes,
this is generally accomplished mechanically. A gripper grabs the
workpiece on one end that is guided through the forming device, for
example the drawing die, and is moved in the direction of traction
by means of a mechanical drive, such as an electric motor. This way
the tractive forces required for the forming process are generated,
which can amount to for example 10 tons. Known mechanical
facilities, however, have the disadvantage that a tractive element
always must be attached to the rod-shaped workpiece to be formed,
which is associated with considerable effort. Moreover, with such
mechanical tractive elements, the speed of the drawing process is
limited due to mechanics. In typical pipe drawing systems, this is,
for example, a maximum of 300 m pipe material per minute. This is
especially disadvantageous with so-called continuous drawing
machines, where a quasi-continuous workpiece such as a wound pipe
of great length is drawn continuously to be formed.
[0004] Proceeding from this prior art, it is the object of the
invention to offer a method for applying compressive and/or
tractive forces on an essentially rod-shaped workpiece where the
use of mechanical gripping elements can be foregone. Moreover a
device for executing such a method shall be provided.
[0005] To accomplish this objective, the invention suggests a
method for applying compressive and/or tractive forces on an
essentially rod-shaped workpiece consisting of an electrically
conductive and/or magnetizable material, whereby a magnetic field
is applied to the material having a gradient in the direction of
the force to be applied.
[0006] By applying a magnetic field comprising a gradient pointing
in the direction of the force to be applied to the rod-shaped
material, a magnetic field is generated in the electrically
conductive and/or magnetizable material through a flow of current
initiated by induction or through an alignment of magnetic poles.
Due to this induced magnetic field and the gradient of the outer
magnetic field, a force that is pointed in the direction of the
gradient of the outer magnetic field is applied on the rod-shaped
workpiece. Depending on the alignment of the gradient of the outer
magnetic field, a compressive force pointing in one direction or a
tractive force pointing in the opposite direction can consequently
be applied on the workpiece. Applying the forces does not take
place mechanically, but purely through the interaction of the outer
magnetic field with the magnetic field induced in the material of
the workpiece based on this field.
[0007] Since with such a method of applying compressive and/or
tractive forces mechanical motion is not required, with this method
for example an advancing speed during the forming process is not
limited by mechanical specifications. Consequently basically higher
speeds can be reached than is the case with systems known from the
state of the art.
[0008] Pursuant to a beneficial development of the invention, the
magnetic field comprising a gradient can be generated by a coil
arrangement subjected to current through flow, having an
inhomogeneous construction. An inhomogeneous design of a coil
arrangement within the meaning of this invention can be realized by
a single coil having an inhomogeneous shape, for example an
interior tapering down conically in the longitudinal direction of
the coil, or a winding density that changes in the longitudinal
direction of the coil, thus generating an inhomogeneous magnetic
field. A coil arrangement consisting of several coils deviating
from one another in their properties, however, should also be
understood by an inhomogeneous construction of a coil arrangement.
Such a coil arrangement allows a magnetic field comprising a
gradient to be generated in a simple manner, whereby the coil
arrangement itself is fixed in space, and the magnetic field is
generated by conducting a flow of current through the coil
arrangement. Such a coil arrangement requires no mechanically
moving parts whatsoever; the compressive and/or tractive forces are
applied on the workpiece exclusively due to the magnetic fields
generated by the coil arrangement.
[0009] In accordance with another advantageous refinement of the
invention, it is provided that the magnetic field comprising a
gradient is generated by at least two coils that are arranged
around the rod-shaped workpiece, whereby the coils are subjected to
current through flow, respectively, for the generation of different
magnetic fields. A coil within the meaning of the invention should
hereby also be understood as individual conductive loops. Within
the framework of this embodiment of the invention two coils of
equivalent design can be arranged around the workpiece, axially
spaced from each other, whereby for the purpose of generating
different fields currents of different strengths and/or phases are
conducted through the coils. When the magnetic field comprising a
gradient is created with such an arrangement, it is possible, with
a large number of coils and suitable control, to achieve a very
exactly controlled course of the magnetic field, which enables an
exactly metered application of compressive and/or tractive forces
on the rod-shaped workpiece.
[0010] For the controlled application of compressive and/or
tractive forces on the rod-shaped workpiece, pursuant to the method
described here in an advantageous refinement of the same, the
current flowing through the coils and/or the coil arrangement can
be modified as a function of the time. This can occur periodically,
whereby the selected frequency is preferably selected in accordance
with a frequency of resonance that is designed as a function of the
material properties and the dimensions of the rod-shaped workpiece.
The frequency at which the most efficient conversion of electric
energy into compressive and/or tractive forces occurs with the
selected coil arrangement with interposition of the magnetic fields
is designated as such a frequency of resonance.
[0011] In order to prevent the coil arrangement from overheating,
the coils can be cooled, if necessary, pursuant to a suggestion of
the invention.
[0012] Pursuant to another advantageous refinement of the
invention, the rod-shaped workpiece, if it is electrically
conductive, can be subjected to current through flow to support the
application of compressive and/or tractive forces. By connecting
the workpiece itself with an external source of power and thus
supplying it by a current, apart from the magnetic field that is
induced by the exterior magnetic field another magnetic field is
generated around the workpiece. An amplification of the force
applied to the workpiece can be attained depending on the direction
of the current flow and the polarity of the exterior magnetic
field.
[0013] The workpiece can be cooled in accordance with another
advantageous proposal of the invention in order to prevent the
workpiece from overheating due to the external magnetic field, as
this can occur especially in the case of periodically alternating
magnetic fields.
[0014] With the method of the invention, rod-shaped workpieces can
be transported or be drawn or compressed by corresponding forming
dies for the purpose of shaping them. The rod-shaped workpieces
only have to consist of an electrically conductive and/or
magnetizable material. Here all electrically conductive materials
come into consideration, but also magnetically polarizable and/or
magnetizable resins or equivalent materials.
[0015] To accomplish the aforementioned objective, the invention
furthermore proposes a device for applying compressive and/or
tractive forces on an essentially rod-shaped workpiece consisting
of electrically conductive and/or magnetizable material, comprising
a coil arrangement that can be acted by a current for creating a
magnetic field comprising a gradient pointing in the direction of
the force to be applied on the workpiece.
[0016] The coil arrangement here can comprise a single,
inhomogeneously designed coil. However it preferably comprises at
least two coils, which can be acted by a current that can be
adjusted individually for each coil. Coils within the meaning of
the invention should be understood not only as coils with several
windings, but also individual conductor loops. Pursuant to an
advantageous refinement of the invention, the individual coils are
arranged concentrically around a workpiece path axially spaced from
one another, along which the workpiece is to be acted upon by
compressive and/or tractive forces.
[0017] Further advantages and features of the invention are
disclosed to the expert from the following description of on
exemplary embodiment based on the sole appended FIGURE,
wherein:
[0018] FIG. 1 illustrates in diagrammatic view an arrangement for
drawing a pipe, whereby the tractive force required for the drawing
operation is applied on the pipe by means of the inventive
method.
[0019] FIG. 1 shows a diagrammatic view of a section of a pipe 1.
The pipe 1 is shown as it is drawn through a die 4 in the direction
of the arrow 8 for the purpose of reducing the pipe diameter. A
pipe section 2 with the initial diameter of the pipe is shown in
the figure to the left of the die 4. In the figure to the right of
the die 4, a pipe section 3 is shown, which has a reduced diameter
as compared to the diameter of the pipe section 2. Moreover a coil
arrangement 5 is depicted, which is composed of a total of four
equivalent coils 5a through 5d, which are arranged in the axial
direction of the pipe 1 at a distance from each other and
concentric to the pipe section 3 around said section. The coils 5a
through 5d of the coil arrangement 5 are connected with a
controllable power source 7 by means of electric lines 6a through
6d.
[0020] With the controllable power source 7, individually different
currents can be supplied to the coils 5a through 5d of the coil
arrangement 5 by means of the electric lines 6a through 6d so as to
create a magnetic field in the area of the coil arrangement 5 with
a gradient running in the direction of the arrow 8. Such a magnetic
field comprising a gradient induces a secondary magnetic field in
the pipe section 3 of the pipe consisting of an electrically
conductive and/or magnetizable material. Due to the interaction
between the magnetic field provided with a gradient that is
generated by the coils 5a through 5d and the secondary magnetic
field a force is generated, which in the example shown acts in the
direction of the arrow 8 on the pipe section 3 and thus on the pipe
1. The pipe 1 is drawn through the die 4 and formed with the help
of this force.
[0021] The controlled power source 7 here can be operated such that
the currents flowing through the coils 5a through 5d, respectively,
can be varied with respect to time, whereby the currents conducted
in the lines 6a through 6d each can have different amounts and/or
can be out-of-phase.
[0022] With the arrangement depicted in a diagrammatic view in the
exemplary embodiment, a tractive force can also be applied on the
pipe for the purpose of drawing a pipe without mechanical aids. The
tractive force that is required for drawing the pipe is generated
solely due to the primary magnetic field that is generated with the
coil arrangement and the secondary magnetic field that is induced
in the electrically conductive and/or magnetizable material of the
pipe. Instead of applying a tractive force on the pipe, a coil
arrangement corresponding to the coil arrangement 5 could be
arranged on the pipe section 2 depicted in the left of the figure,
wherein the coils 5a through 5d should be switched such that a
compressive force that also acts in the direction of the arrow 8 is
exerted on the pipe end 2.
[0023] The embodiment shown serves only to explain the invention
and is not restrictive. The coil arrangement 5 in particular can
comprise a number of coils that differs from the four depicted
coils 5a through 5d. Also, to reinforce the generated compressive
and/or tractive force, a pipe consisting of conductive material can
be connected to the power source and thus be subjected to current
through flow.
LIST OF REFERENCE NUMBERS
[0024] 1 Pipe
[0025] 2 Pipe Section
[0026] 3 Pipe Section
[0027] 4 Die
[0028] 5 Coil Arrangement
[0029] 5a Coil
[0030] 5b Coil
[0031] 5c Coil
[0032] 5d Coil
[0033] 6a Electric Line
[0034] 6b Electric Line
[0035] 6c Electric Line
[0036] 6d Electric Line
[0037] 7 Controlled Power Source
* * * * *